i think your best bet is to just start calling around and see if they have any decommissioned kegs that they are willing to part with. alternatively, you could try posting an ad on craigslist to see anyone has an old beater sitting around their property (that's where i found mine). so long as the inside hasn't been touched, you should be OK.

ive done all of the above. it seems that most of the breweries lease their kegs from microstar based inColorado and when they have a bad keg, it gets sent back there for destruction or repair. the few recyclers ive found arent willing to resell their scrap even for fair market price, may just have to buy a prebuilt keggle from my LBHS, even though they are pricey.